How to figure the q10 temperature coefficient

Written by jim dorsch

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The Q10 coefficient tells how fast the rate of a reaction increases with temperature. (chemical experiences image by Sergey Galushko from Fotolia.com)

The Q10 temperature coefficient is the factor by which a rate of reaction (such as a chemical reaction) increases for each ten-degree increase in the temperature, measured in degrees Celsius. Q10 is defined by the equation Q10 = (R2/R1) ** [10/(T2-T1)], where the double asterisks denote the exponential function and Rn = the rate of reaction at temperature Tn. If you measure the reaction rate at any two temperatures, you can enter the rates and temperatures in this equation to solve for Q10.

Skill level:

Moderate

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Things you need

Scientific calculator

Paper and pencil

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Instructions

1

Measure the rates of a reaction at two temperatures. Call the rates R1 at temperature T1 and R2 at temperature T2. Write the values of R1, R2, T1 and T2 on a piece of paper. This will help you to avoid confusion.

Divide 10 by your answer from Step 3. In the example, you compute 10/30 = 0.333. Write that down.

5

Raise R2/R1 to the power 10/(T2-T1). You determined R2/R1 in Step 2 and you computed 10/(T2-T1) in Step 4. In the example, you raise 3 to the power 0.333. Perform this computation on the Scientific Calculator (see Resources) by entering "3", pressing the "y to the x" key (the first key in the third row), entering ".333" and pressing the "=" key. The answer is 1.44. This is the value of Q10.

Tips and warnings

You must use temperatures in degrees Celsius to compute Q10. You can convert a temperature F in degrees Fahrenheit to the temperature C in degrees Celsius with the equation C = (F - 32) x (5/9). For example, if F = 212, then C = (212 -- 32) x (5/9) = 180 x (5/9) = 100.